Field of the Invention
The invention relates to a platinum complex for an organic light-emitting diode (OLED), and more particularly, to a platinum complex having a carbene fragment, an OLED using the platinum complex, and a nitrogen-containing heterocyclic bidentate chelate having a carbene unit that is for forming the platinum complex.
Description of Related Art
An organic electroluminescent apparatus generally contains an organic light-emitting diode (OLED) and a driving element. In the OLED, an organic material capable of emitting visible light after being excited is used as a light-emitting layer. The light-emitting layer usually includes a phosphorescent material, because such material can utilize a single-state exciton and a triple-state exciton at the same time to effectively increase the luminous efficiency of the OLED.
The blue-light luminous efficiency of known compounds having a maximum light-emitting wavelength of 470 to 530 nm is generally poor. For instance, U.S. Pat. No. 6,963,005 discloses a tetra-coordinated platinum (II) complex formed by chelating one O—O monoanionic bidentate chelate, one C—P monoanionic bidentate chelate, and one central platinum (II) ion. Inorg. Chem., 2007, 11202—discloses a tetra-coordinated platinum (II) complex represented by the following formula (Y represents pyrazole or chlorine), and the solid quantum yield thereof can only reach up to 56%.
